1. Field of the Invention
The present invention relates to a torque converter, and more particularly to a elliptic torque converter in which the axial length of the torus has been shortened.
2. Background Information
A torque converter is a device that includes a torus having three types of vane wheels (an impeller, a turbine, and a stator), and transmits power by means of a fluid inside the torus. Among these types of torque converters, there are those in which the ellipse of the torus has been reduced in the axial direction. By changing the torus to an elliptical shape, the axial length of the entire torque converter will be shortened, and thus the torque converter can be placed inside a space that is limited in the axial direction.
In addition, a lockup device is provided in a space in the torque converter between the front cover and the torus. The lockup device serves to mechanically transmit the torque of the front cover to the transmission side. The lockup device includes a clutch connecting portion and a damper mechanism. The clutch connecting portion is designed so that it couples with or releases from the front cover in accordance with changes in the hydraulic pressure within the torque converter. The damper mechanism includes, for example, a plurality of torsion springs. The torsion springs function to absorb and dampen vibrations in the torsion direction when the lockup device is in the engaged state.
Plates which include a plurality of friction surfaces continue to be added to the lockup device in accordance with recent increases in engine torque.
In addition, torque converters which transmit torque by means of a fluid only when the vehicle is started, and in which the lockup device is connected at a speed of 10 km per hour or higher, for example, have recently been disclosed in the prior art. With a structure like this in which the lockup region is enlarged, it is desirable to improve the performance of the torsion springs in order to sufficiently absorb and dampen torsional vibrations in response to changes in the torque from the engine.
Thus, it will be necessary to increase the length of the lockup device in the axial direction in order to add plates thereto and to improve the capabilities of the torsion spring.
In view of the above, there exists a need for a torque converter which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.